1. Field of the Invention
The present invention relates generally to digital x-ray imaging and, more particularly, relates to methods and apparatuses for removal of scatter using two-dimensional, single-energy x-ray imaging.
2. The Prior Art
Reducing scatter is one of the best ways to improve image quality in x-ray imaging. For most imaging systems using two-dimensional detectors for human body imaging, the ratio of scatter to the primary signal is generally as high as between 50% and 100%. Randomly scattered x-rays tend to reduce image contrast, produce blurring, and reduce signal-to-noise ratio. Currently, clinical x-ray imaging uses the traditional Bucky grid for relieving adverse scatter effects. However, the Bucky grid is a rather inefficient and crude device. Even with the best grid design, the Bucky grid can only reduce the scatter to 30% or 20% of its total intensity, with a price being an increase in the patient's x-ray exposure by two to four times. Moreover, the Bucky grid was invented 90 years ago, largely designed for use with x-ray films, when only qualitative analog imaging was performed. No quantitative requirement existed. Recently, with the development of highly sophisticated large format integrated semiconductor x-ray detector arrays, an essentially new method for eliminating scatter interference in digital x-ray imaging is needed.
U.S. Pat. Nos. 5,649,997 and 5,771,269, and the disclosure of U.S. patent application Ser. No. 09/025,926 provide a rigorous scientific solution to the scatter problem. By using a dual-energy method, scatter can be essentially eliminated from x-ray images with a high accuracy that is limited only by that of the experimental data.